1. Field of the Invention
The present invention relates to the stabilization of solutions of organic compounds of hexavalent chromium in hydrocarbon solvents, and, more especially, to the stabilization of such solutions utilizing stabilizing amounts of partial esters of phosphoric acid.
2. Description of the Prior Art
It is known to this art that organic chromium compounds, and in particular its carboxylic acid salts, its chelates with dicarbonyl compounds or the chromates of tertiary alcohols, are well adapted for the catalysis of various reactions, such as the dimerization of diolefin compounds, the oxidation of cycloaliphatic or alkylaromatic hydrocarbons with air, the hydrogenation of olefinic double bonds in hydrocarbon polymers, the decomposition of organic hydroperoxides, or the crosslinking of polymers comprising carboxyl functions by means of epoxy compounds. And the chromates of tertiary alcohols remain useful as oxidizing agents.
To carry out the aforesaid various reactions, it is often times advantageous to use the chromium derivatives in the form of a solution in a hydrocarbon solvent, such as an alkane, cycloalkane or aromatic hydrocarbon solvent. In the case of reactions carried out continuously, it is typically convenient to have a supply of catalyst solution readily available. However, it has been found that these solutions are not stable with passage of time and ultimately result in the precipitation of the metal as chromium oxide. A phenomenon of such type is especially deleterious because it causes both blocking of the pumps and feed pipes and variations in the concentrations of the catalyst solutions, and this jeopardizes the steady progress of the reactions in question.
This precipitation phenomenon is the more marked, the longer the solutions are stored.